Mechanical rectifier.



R. P. JACKSON.

MECHANICAL RECTIFIER.

APPLICATION HLED JUNE 9, 19x4.

1 1 99 469 I Patented Sept. 26; 1916.

WITNESSES: INVENTOR Ray F! Ja'cKson.

ZTTONEY UNITED STATES PATENT OFFICE.

RAY P. JACKSON, 01 EDGEWOOD PARK, PENNSLYVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MECHANICAL RECTIFIER Specificationof Letters Patent. Patented Sept. 26, 1916 Application filed. June 9, 1914. Serial No. 843,950.

To all'whom it ma concern:

Be it 'known t at I, RAY P. JACKSON, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Mechanical Rectifiers, of which the followtifiers of the rotating type; Fig. 2 is a diagrammatic view of a modified form of the system shown in Fig. 1; and Fig, 3 is a diagrammatic view of my invention as applied to a rectifier of the vibrating or Giglio type. In the types of rotating and vibrating rectifiers which have been placed on the market, heretofore, great difiiculty has been experienced in preventing sparking when current flow is interrupted at the ends of current waves of the desired polarity. While it is possible to secure sparkless operation with constant load, frequency and wave form, if any of these factors change to any great extent, sparking may ensue. By my invention, I am enabled to obtain sparkless rectification throughout a wide range of variation in any ofthese factors.

Referring to the orm of my invention shown in Fig. 1, 4 is any desired source of singlebase alternating current, such, for

examp e, as the secondary winding of a transformer 5 having a primary winding 6 supplied from mains 7 and 8. A load 9, of

any desired character requiring unidirectional current, such, for example, as a battery, is connected between the mid point 10 of the source 4 and a wire 11' connecting brushes 12 and '13. A synchronous motor 14 drives a shaft 15 in synchronism with the frequency of the source 4. The shaft 15 carries two slip rings 16 and 17 and two rectifying devices 18 and 19. Brushes 20 and 21,, connected respectively to the terminals of conductor 22 supplies alternating current to one terminal of the armature of the synchronous motor 14 and also to conducting segments 23 in'the rectifying device 18. In a like manner, the slip ring 17 is connected to a conductor 24 mounted on the shaft and supplying alternating current to the other terminal of the armature winding of the synchronous motor 14 and to conducting segments 25 in the rectifying device 19.

Direct current excitation for the synchron: ous motor 14 is derived from the battery 9 or from any other suitable sourceof direct current. Each of the four conduc'ting'segments 23 in the rectifying devices 18 ex tends over an .arc somewhat less than 45 in length and, accordingly, the peripheral spaces intervening therebetween extend somewhat more than 45. Conducting segments 26, of relatively short length, are disposed a short distance behind each of the conducting segments 23, for a purpose to be hereinafter pointed ou The conducting segments 26 are all connectedto a common conductor 27, which, in

turn, is connected to a conducting segment 28 covering an arc of substantiall 45 Four brushes 29 are so mounted as to e successively engaged by the conducting segment 28, and each of the brushes 29 is connected to a terminal ofa ballast lamp 30. The remaining terminals of the ballast lamps 30 are all connected to the left hand terminal of the source 4. Each of the ballast lamps 30 comprises a gas-tight conof the first class, such, for example, as fine iron wire, which has a comparatively steep temperature-resistance characteristic. Any other type of resistance element having small heat capacity, high heat-radiating qualities and a rapidly rising temperature characteristic may be employed in place of the ballast lamps 30. In a similar manner, the rectifying device 19 is provided with small conducting segments 31, all of which are connected to a conducting segment 32 adapted to make contact successively with.

brushes 33 connected respectively to ballast lamps 34 which are, in turn, connected to the right hand terminal of the source 4.

- Having thus described the construction of my device, the operation is as follows: Assum ing the, shaft to be driven in synchnfihism with frequency of the source by the synchronous motor 14 and assuming the brushes and the conducting segments to be properly adjusted, a positive wave flowing from the right hand terminal of the source 4 through the brush 21, the slip ring 17 and the conductor 23 to the segments 25 will bepermitted to fiow through the load 9 because of the fact that the brush 13 has just come into contact with one of the segments 25.

' At the same instant, current fiow of the preceding wave from the upper segment 23 to-the brush, 12 has just ceased and the brush 12 has come into engagement with the upper cool sufic' iently in the time given, the numberof conducting segments may be greatly auxiliary contact 26. Accordingly, any energy that would manifest itself as a spark, because of the fact that the preceding current wave is lagging slightly, or because of the fact that the field of any inductive device in the circuit is collapsing, will be I forced to traverse the conducting segment- 28, the upper brush 29 and a corresponding ballast lamp 30. The flow of current in the ballast lamp causes an extremely rapid rise of the resistance therein and an extremely quick absorption of the energy of the cur-- them. In the particular construction set forth, the synchronous motor should rotate at onequarter the fre acne and four cycles be 'rectlfied or each revolution of the rectifying device 18. It will thus be noted that each of the ballast lamps 30 is called upon "to ahscrbth'e residual-energy onl "a t the'en'd of-each" fourth cycle or of eac e1 'hth'wa'v'ei During the intervenin time, t e? resistance element therein" wi V cooland-its resistance'will. fall to acom parativelylow value Obviously, if the resistance elements in the ballastlamps do not increased and thenumber of ballast lamps increased in proportion, so that any desired amountof-time may be given saidelements to cool between successive periods of iv y Referring to the formof my device shown in Fig. 2, source of alternating current 33 is connectedto slip 36 and 37 driven absorbed therein.

shown in Fig. 2 preferable to that shown in of the source by a synchronous motor 38, which also drives rectifying devices 39 and 40, all as in the deviceshown in Fig. 1. A plurality of main conducting segments 41 in the rectifying device 39 are connected directly to one terminal of the source 35 through the slip ring 37 a shaft conductor 42 and a conducting bond 43. Axially disposed-behind each of the segments 40 is an auxiliary segment 44, and connected between these auxiliary segments and the conducting bond 43 are ballast lamps 45 mounted directly upon the rectifyin device 39. In a similar manner, the resti ying device 40 is provided with a conducting bond 46, main conducting segments 47, and auxiliary conductin ents 48, the latter being connected to t e bond 46 through ballast lamps 49. Brushes 50 and 51 are adapted to make contact with the segments 41, 44, 47 and 48, respectively, and are connected to one terminal of a load 52, the other terminal of which is connected to the mid point 53 of the source 35. When a current wave of the desired polarity is flowing through a main conducting se ment in one of the rectifyin devices, the rush in the other rectifying evice is either bearing upon an auxiliary conducting segment or is bearing upon an insulatin segment, and vice versa. Accordingly, a ter a brush has conducted the major portion of a current wave of the desired polarity, it passes to an auxiliary segment, and thelast portion of the current wave, together with all other spark-producing current, is forced to traverse a ballast lamp and to have its ener I consider the device Fig. 1, since the connections are much simpler, fewer brushes are employed, and the ballast lamps dissipate their heat much more quickly because they are moving rapidl through the air.

loo

eferring to the form of deviceshown in Fig. 3, the terminals of a' source of alter nating current 54 are connected to adjust able contact members 55 and 56, res ectively. A'bar 57, of magnetic materia is pivotally mounted and carries'two spring contact members 58 and59 adapted to make contact, respectively, with the contact mem-f 'bers 55 and 56. Two l electromagnets 60 es ad's:

and 61 are'disposedwith" like po cent the respective endsof the bar 57. electromagnets'fifl and 61 are energized. by alternating current fromthe source'54, and the phase jungle of saidcurrent may be varied by an adjustable. resistance element 62. The armature 57 is ma etized by direct current from. any suitab e source, such, for example, as a load battery 63, through the instrumentality of windings 64. Owing to the interaction between" the unidirectionafil flux in the armature 5,7 and the alter nating fiuxin themagnets 60 and 61, the

Company, May 23, 1916, on an application Mounted adjacent.

filed by Edgar Giglio. the contact members 55 and 56 I are additional contact members 65 and 66. A ballast lamp 67 is connected between the contact member 55 and the contact member 65, and a ballast lamp 68 is connected between the contact member 56 and the contact member66. The armature 57 carries two springmounted contact members 69 and 70 that are adapted to make contact, respectively, with the contact members 65 and 66. When the armature 57 is in the mid position, as shown,

the adjustment is such that the contact members 69 and 65 are much closer together than are the contact members 55 and 59, and the. contact members 66 and 70 are much closer together than are the contact members 56 and 58. Accordingly, when the armature 57 is vibrated, contact will be made between the members 65 and 69 earlier than it will bev made between the members 55 and 59 andwill be broken subsequently, and contact will-be made between members 66'and 7 O earlier than between members 56 and 58 and will be broken subsequently thereto. As is well known in the art, with devices of this character, current waves of thedesired polarity will flow from the right hand terminal of the source 54 through the contact member 55 to the contact member a wire 71. Alternate waves will flow from the left hand terminal of the source 54 through the contact members 56 and 58 and the load 63 to, the mid point of the source. At the instant that contact. is broken between the members 56 and 58, slightly before the end of the current wave which is flowing, current will flow through the ballast lamps 68 and the contact members 66.and 70, and the break between members 56 and 58 will be shunted by a low resistance. Current fiow being transferred to the ballast lamps, the resistance of the latter will rise with extreme rapidity'and, at the time contact is broken between members 66 and 70, the current will have been reduced to such an extremely small amount, owing to the higher resistance of the member 68,

- at this time, that there will be practically no sparking between the members66 and 70. A similar action will take place'at the right hand end of the apparatus.

While I have shown my invention as Pmbodied in three distinct forms, for purposes of illustration, I do not desire to have it restricted thereto but wish it to cover broadly any form of rectifier wherein a current path of low resistance is provided for waves of the desired polarity, and a resistance element having a steep temperature resistance characteristic, small 'heat capacity, and good heat radiating qualities is inserted in said path for an instant at or near the end of each current wave of the desired polarity.

I claim as my invention:

1. The method of preventing sparking in mechanical rectifiers which comprises inserting a resistance element composed of a conductor of the first class, in the current path during the latter portion of a current the flow of current by increasing resistance of said conductor, and then opening the current path.

2. The method of preventing sparking in mechanical rectifiers which comprises inserting a resistance element, composed of a conductor of the first class of small heat capacity and high heat dissipating capacity, in the current path during the latter portion of a current wave of the desired polarity, diminishing the flow of current by the increasing resistance of said conductor and then opening the current path.

3. The combination With a source of alternating current, of a load, a rectifying device comprising a plurality of main conducting segments and a rotatably mounted slip ring, the conducting segments being separated by spaces slightly longer than the segments themselves, a relatively small conducting segment associated with each main conducting segment and angularly displaced therefrom by a small amount away from the direction of rotation, low-resistance connections between the main segments and the slip ring, resistance elements comprising conductors of the first class of small heat capacity connected between each of the anxiliary segments and the slip ring, contacting means for the segments and the slip ring, and connections from one terminal of the source, through the rectifying devicev 7 wave of the desired polarity, diminishing nating current, of a load, a rectifying device comprising a plurality of main conducting segments and a rotatably mounted slip ring,

the conducting segments being separated by. spaces slightly longer than the segments 'rection of rotation, low-resistance connections between the main segmentsand the 'slip ring, ballast lamps connected between each of the auxiliary segments and the slip ring, contact means for the segments and the slip ring, and connections from one tonminal of the source through the recti ing a current Waves of but one polarity are allowed. to pass from each terminal of the source through the load, and means for mementarily inserting a I resistance element comprising a first class conductor of small heat capacity in the connection between. a terminal of the source and theload during the last portion of flow from each desired current wave and for an instant thereafter.

6. The combination with a source of alternating current, of a load, means whereby current waves of but one polarity are allowed to pass from each' terminal of the source throughthe load, and means for mo mentarily inserting a ballast lamp in the connection between a terminal of the source a and the load during the last portion of flow RAY P. JAo soN;

Witnesses:

B. B, HINns, A. M. LUNDYO 

